Innovative advances in breath analysis provide opportunities for non-invasive personalized biofeedback for medical conditions. Cavity ring-down spectroscopy (CRDS), in particular, provides a highly accurate, precise, and rapid table-top methodology for measuring stable isotopes in exhaled breath. Breath isotopes provide information about metabolic processes within the body. One such application is the decrease in 13C natural abundance in breath, a biomarker for the catabolic state.
A noninvasive, non-doping, rapid stable isotope method to discern the onset of the catabolic state by detecting isotopic changes in the exhaled CO2 in breath was described in U.S. Pat. No. 5,912,178 (the '178 patent). The relative health of an organism was determined by comparing the sampled ratio (C13:C12) to a baseline ratio in the organism by testing breath samples in a mass spectrometer, for example. The methods disclosed in the '178 patent allow for a non-invasive determination of net catabolic processes of organisms experiencing altered organ function or a deficit in nutrient intake.
Similarly, in U.S. Pat. No. 7,465,276 (the '276 patent), the relative amounts of first and second breath isotopes are measured over time to determine if an organism is experiencing a viral or bacterial infection. Advantages of the method of the '276 patent are that breath samples from an isotopically unenriched organism can be monitored for changes in isotope ratios over time to determine if the organism is experiencing a bacterial or viral infection. A baseline measurement from the healthy subject is preferred so that changes from the baseline can be measured that are indicative of infection. Measurements can be obtained over several hours or even several days so that the change in isotope ratio from the baseline ratio can be determined.
In addition, U.S. Pat. No. 8,512,676 describes the use of oscillation modes in breath isotope ratio data to identify an “unhealthy” state in an organism. Changes in the frequency and/or amplitude of the oscillation modes can be correlated with the health of an individual. Advantageously, advances in cavity ringdown spectrometry allow for the continuous collection of breath isotope data which permits the identification of oscillatory patterns within the breath isotope data. The identified oscillation modes are particularly useful in determining the transition from a healthy to an infected state in an organism within the short-term infection period, e.g., 30 minutes to 2 hours.
While previous methods using determination of breath isotope ratios are well-suited for their intended purpose, it is desirable to find additional uses for breath isotope ratios as a non-invasive biofeedback tool.